The present invention relates to a treatment tool for an endoscope.
Conventionally, various types of treatment tools for endoscopes have been provided, including a tip portion as a treatment instrument that is adapted to be protruded and retracted from a tip end of a sheath being inserted through an instrument channel of the endoscope. The tip portion is protruded and retracted by advancing and retracting an operation wire arranged in the sheath in an axial direction thereof.
Such a treatment tool is generally provided with a fluid channel to convey water forwardly therethrough to a distal end of the treatment tool so that the tip portion with in vivo tissues such as mucous membranes is cleaned, and an example of such a treatment tool is disclosed in Japanese Patent Provisional Publication No. HEI10-165359.
The above referenced treatment instrument is provided with a fluid channel independently from an operation wire, however, such a treatment tool may use an inner tube, in which the operation wire is arranged, as the fluid channel to convey water therethrough.
When the treatment tool is provided with the independent fluid channel, a distal opening of the fluid channel is arranged in an offset position with respect to a diameter of an outer tube. Due to the offset position of the opening, a front portion of the treatment instrument with mucous membranes stained, which is most often required to be cleaned, may not be washed substantially with the ejected water.
When the treatment tool uses the inner tube as the fluid channel, the opening is arranged in the center of the diameter, therefore the front portion of the treatment instrument may be washed. However, the fluid channel, which is partially occupied by the operation wire, may not be capable of delivering enough water.
It should be noted that the above referenced treatment tool is not provided with a bending mechanism to control an orientation of the treatment instrument in an arbitrary direction by a remote operation from a user, however, such a mechanism is desirable to have the treatment instrument lead in a targeted area for the treatment.
Japanese Patent Provisional Publications No. HEI9-262239 and No. HEI11-42232 disclose treatment tools with such bending mechanisms. However, tip portions of these treatment tools are not configured to be protruded and retracted from distal ends of sheaths. Further, such treatment tools are required to have additional operation wires to bend distal portions inside the sheaths, which make the structures the operations of the treatment tools complicated.